We had it in the 1990's
We developed Mondex in the 1990's https://en.wikipedia.org/wiki/Mondex
But it was inadequately publicised and so the public did not accept it. Mondex really is as anonymous as cash, because the money is stored as data in the Mondex wallet (smart card), and can be transferred directly to any other Mondex wallet with no external record of the transaction being kept, and no connection or data transfer to anywhere else. It is effectively exactly the same as having paper money & coins in a physical wallet. Transactions are fast because there is no need to check for approval from a third party. The downside is that just like cash notes, if your Mondex card is lost or destroyed, you lose your money. Therefore, like a physical wallet, it is not a good idea to have too much money in the card at any one time.
The card can however be secured with a PIN so that it is not attractive to a thief. Another advantage is that money can be transferred from one Modex card to another via a data connection (e.g. modem or Internet), so you can pay people anywhere in the World remotely (as well as anonymously).